Apparatus for forging crankshafts and like parts

ABSTRACT

This apparatus for forging crankshafts and like parts comprises a fibrating apparatus proper and a separate distributor adapted to control the movable elements of the fibrating apparatus through hydraulic transmission means.

United States Patent Ruget 1 Sept. 5, 1972 [54] APPARATUS FOR FORGING CRANKSHAFTS AND LIKE PARTS References Cited [72] Inventor: Gabriel Ruget, Saint-Etienne, UNITED STATES PATENTS rance 2,747,253 5/1956 Conchon ..29/6 [73] Assignee: Compagnie des Ateliers et Forges de la Loire, Paris, France Primary Examiner-Charles W. Lanham Assistant ExaminerMichael J. Keenan [22] Flled' June 1970 Attorney-Wenderoth, Lind & Ponack [21] Appl. No.: 48,939

Related US. Application Data r h fABSTRAC: haf d k is apparatus for orging cran s ts an li e parts [63] Continuation of Ser. No. 655,148, July 21, comprises a fibrating apparatus proper and a Separate 1967 abandoneddistributor adapted to control the movable elements of the fibrating apparatus through hydraulic transmission [52] US. Cl. ..72/402, 29/6, 72/453 means [51] Int. Cl. ..B2ld 41/00 [5 8] Field of Search ..29/6; 72/402, 412, 453 13 Claims, 10 Drawing Figures PATENTEDSEP 5H7? 3.688.552

SHEET 1 BF 4 n6 0 PRIOR ART PATENTEDSEP 51912 SHEET 2 [IF 4 PATENTEDSEP 5 I972 SHEET 3 BF 4 Jmfm UM. my $41.44! @4 PATENTEDSEP 1912 SHEET 4 0F 4 E 7, Q 36a 34a v m aqua APPARATUS FOR FORGING CRANKSHAF TS AND LIKE PARTS This application is a continuation of Ser. No. 655,148, filed July 21,1967, now abandoned.

This invention relates to apparatus for forging crankshafts with multiple throws set at any desired relative angles without twisting of the material, thereby providing a continuous grain flow, and more generally forgings requiring upsetting or offsetting movements or both movements in combination. The manufacturing process is intended to forge crankshafts by a method in which the geometrical center line of the ingot or billet will follow the neutral axis of the finished crankshaft, the peripheral portions remaining in the vicinity of the surface.

Forging apparatus using this process are described in US. Pat. Nos. 2,535,295 and 2,747,253.

With the above and other objects in view which will become apparent from the detailed description below some preferred forms of the invention are shown in the drawings in which:

FIG. I is a diagrammatic view of the prior art;

FIG. 2 is a longitudinal section of a C.G.F. apparatus;

FIG. 3 is a longitudinal section of the hydraulic actuator unit;

FIG. 4 is a plan view showing the power rams of the cradles;

FIG. 5 is an end view of the cradles;

FIG. 6 is an end view of a rotary angular positioning device;

FIG. 7 is an end view of the center tool;

FIG. 8 is a longitudinal section showing an optional design ofa C.G.F. apparatus;

FIG. 9 is a section through the center line of a column and the axis of the upsetting rams of the apparatus shown in FIG. 8; and

FIG. 10 is a top view of this optional design.

An apparatus such as shown in the above patents, which will be called C.G.F. apparatus (i.e. continuous grain flow process forging apparatus) in the following description, is construed as shown diagrammatically in FIG. 1.

It comprises essentially:

A lower base plate 1 supported by the bed 2 of a press;

A pair of sliding cradles 3, 3' supported by slideways 4, 4 formed on said base plate 1;

An upper cross member 5 integral with the upper cross-head 6 of the press.

Crankshafts are forged from bars which are conveniently preformed with constrictions separated by enlarged parts or swells. The swells constitute in general the webs or flanges, whereas the constrictions constitute the journals or crankpins. The initial blank may also be plain from end to end. In this case, the swells are formed directly on the apparatus by upsetting.

When, following the press action, the upper cross member 5 is lowered, it produces the movement of cradles 3, 3 towards each other, by means of inclined slideways, 7, 7'. This movement induces the upsetting of the metal on each side of the intermediate portion between the two end dies closed by the pressure of rams 9 and 9' formed in the upper cross member.

As the cradles 3 and 3 are moved towards each other, the upper cross member 5 moves downward the upper part of a crankpin die onto the lower part of said crank pin die which is supported by a ram 11, whereby the metal is set off transversely.

The combination of these two orthogonal movements of the C.G.F. apparatus form a throw on the blank.

In FIG. 1 the chain dotted lines show a throw formed at the end of the forging process on a plain blank between the cradles 3 and 3', and the lower crankpin die 11 and the upper crankpin die 10.

The inconveniences of this C.G.F. apparatus are set forth hereafter:

Such a crankshaft forging process is particularly advantageous for average and large size crankshafts. Now, as a rule, experience teaches that the forging capacity of a C.G.F. apparatus of the type set forth hereinabove used in a given press is rather limited. This limitation is generally due to the space available between the columns of the press, which prevents the use of a C.G.F. apparatus of suitable size. Besides, it occurs that the tonnage of the press is not high enough to upset the largest webs likely to be forged. It is believed that roughly only one-third of the tonnage of the press is available to this end in the heretofore employed apparatus. However, the upsetting action of the press can be increased to a certain extent by adding auxiliary rams on the C.G.F. apparatus for acting upon the sliding cradles thereof in conjunction with the press crosshead.

To forge a crank on a C.G.F. apparatus the swell can be upset down to the predetermined thickness of the web, thereby allowing the metal to flow and take freely its shape; this is the so-called open die forging. It is also possible to jointly impose a predetermined shape to those webs; this is the limited forging or closed die forging. The more the desired profile differs from the open die forging profile, the more the tonnage required for upsetting must be high. An open die forged web, which allows a given machined web to be obtained, mostly requires a considerable machining allowance, which involves a high increase of the machining cost. This machining allowance cannot be reduced for cutting down the final cost of a crankshaft unless the latter is profiled by means of a closed die forging operation in which the final dimensions are approached as closely as possible.

In this operation, the nearer the approach to the final dimensions, the higher the forging tonnage to be implemented. Under these conditions, it appears that when the upsetting force of a C.G.F. apparatus is limited not only the size of the largest web that can be forged in open dies is limited but also and all the more the size of the largest web that can be forged in closed dies, especially if minimum machining allowances are contemplated.

In conventional C.G.F. apparatus the proper angular setting of the last shaped crank, with a view to ensure the desired orientation of the next crank, is obtained by using jigs which are to be replaced in the sliding cradles each time one more crank has been forged. Thus, to forge a batch of identical crankshafts, it is necessary to forge one crank at a time and all the cranks of the same number on all the bars of the same batch whereafter the jigs are set in another angular position for forging the cranks of the next batch. As a rule, this method permits of forging only one crank per heat on each crankshaft. Under these conditions, each blank must be heated as many times as there are cranks to be forged therein. This technique is therefore very costly, not so much on account of the direct cost of heating proper, but rather for the time necessary for carrying out this operation, which frequently implies relatively long idle periods both for the forging equipment and for the considerable gang necessary for operating this equipment.

The relatively great number of men constituting this gang is due mainly to the difficulty of handling the blanks which must be introduced in the axial direction of the cradles into the forging apparatus. Now this bandling operation is delicate and time-consuming. Finally, it is worth pointing out that the installation of the C.G.F. apparatus on the press and its removal therefrom involves non-productive operations requirin g considerable time and labor.

It is the essential object of the present invention to provide a new C.G.F. apparatus for the purpose set forth which eliminates the drawbacks discussed hereinabove.

According to the present invention, there is provided an apparatus for forging crankshafts or forgings having upset and/or offset parts and giving to these forgings a continuous grain flow and small machining allowances, said apparatus comprising on the one hand a forging machine including two end dies adapted to grip spaced portions of the bars and adapted to slide horizontally toward each other to upset the metal and a center tool adapted to offset the intermediate portion and forge the crankpins, movable vertically upward and downward between said end dies, on the other hand a separate three cylinder actuator unit, which can be placed under an ordinary forging press in order to hydraulically transmit the power output of the press to the forging apparatus itself.

According to a preferred embodiment of this invention, the apparatus installed outside of the press is actuated by the latter from which the power is taken off by the hydraulic actuator unit, a three-cylinder unit installed on the press which subsequently distributes the hydraulic fluid into the C.G.F. apparatus for performing its main movements.

Conveniently, the three-cylinder unit is adapted to multiply at least by two the thrust produced by the press.

The C.G.F. apparatus proper comprises two sliding cradles holding the blank and a transversely acting center tool. The hydraulic actuator incorporates three hydraulic cylinders of the piston type. The two lateral cylinders are identical and each hydraulically connected to the rams of the C.G.F. apparatus which control the movements of the cradles for upsetting the blank metal. The central cylinder, hydraulically connected to the cylinders controlling said center tool, offsets the pin transversely outwards during the upsetting movement forming the two webs of the crank.

According to a modified form of embodiment of this invention, the sliding cradles as well as the center tool of the C.G.F. apparatus are actuated from a common hydraulic power station, without resorting to a forging press.

This invention is also concerned with sliding cradles adapted to be opened to permit the introduction from above of the blank to be forged, locking means being provided to prevent the opening of said cradles, even to a very limited extent, during the forging operation.

According to another feature characterizing this invention one of the cradles comprises a rotary mounted die for. the proper angular setting of the throws of the blank being forged.

The center tool may comprise a cavity closed by the forging faces of the two sliding cradles, this cavity con stituting a die for shaping the webs of the cranks to be formed.

The apparatus according to this invention comprises, on the one hand, the above defined forging apparatus proper A, installed outside the press and, on the other hand, a movable three-cylinder unit B, arranged under the press and taking off the power therefrom for actuating the apparatus A.

The actuator unit incorporates three hydraulic cylinders of the piston type, i.e., two lateral identical cylinders 11 and 11a and a central cylinder 12. Both lateral cylinders are each connected to a corresponding cyldinder 13 or 13a actuating respectively the sliding cradles l4 and 14a of a new C.G.F. apparatus. The central cylinder 12 is connected to the cylinders 15 which actuates the center tool 16 adapted to offset the crankpin during the forging operation.

During its downward movement, the upper crosshead 17 of the press drives any or all of the rams of the three-cylinder actuator B, each of them at a preset point of its operative stroke, thereby the rams forcing the hydraulic fluid contained in their cylinders into the cylinders of the new C.G.F. apparatus A, with which they communicate, so as to operate this apparatus The forging apparatus proper A comprises a base 18 supporting a pair of parallel rods 19, 19a which guide the sliding cradles i4 and 14a. The hydraulic jacks are composed of these rods and cylinders formed in the cradles themselves and the pistons 20, 20a are fixed on said rods and are therefore stationary.

Each of the sliding cradles 14 and 14a is shaped so as to support dies which grip the blank 21. A rotary die 22 (FIGS. 5 and 6) actuated, for example, through a chain transmission 23 from a motor-reducer unit 24 is provided for locking the n the throw in the required angular position relative to the (n+1) the crank about to be forged.

Two upper dies 25, hinged at 27 and moved by two hydraulic cylinders 26, hold the blank in position in each cradle during the forging.

The center tool 16 is hinged on a moving center cross member 30 which is moved vertically upward and downward by rams 15 connected with the central cylinder 12 of the actuator unit B. The cross member 30 is guided during its movements by the base 18 of the apparatus. When the blank is positioned on the ap paratus the two jaws 16a, actuated by two cylinders 28, clamp the part to be offset and are locked by the retainer 31 which engage the heels 32 of the jaws and which is actuated by the cylinder 33.

The cylinders 26, 28 and 33 as well as the cylinders which control the return movements of the sliding cradles are fed directly from an auxiliary hydraulic pressure generator not shown.

The initial position of each piston of the three cylinders actuator B may be adjusted so that, during a first portion of its stroke, the press will overpower the ram 13 and 13a actuating the sliding cradles and then, during a second portion of its stroke the press will drive the ram of the central cylinder which actuates the center tool. Thus crankshafts can be forged from plain bars and the swells or enlarged parts can be formed in the apparatus according to this invention as it was already made in the conventional C.G.F. apparatus.

By a direct communication or by pass it is possible to interconnect the two lateral cylinders 11 and 11a ofthe hydraulic actuator unit B in order to balance the pressures in the cylinders which actuate the two sliding cradles and therefore making equal the upsetting thrust of said cradles.

FIGS. 8 to it) illustrate diagrammatically a modified form of the new C.G.F. apparatus following this invention. In this embodiment the sliding cradles 34 and 34a are actuated by single acting cylinders 35 and 35a respectively connected to the cylinders 11 and 11a of the hydraulic actuator unit. They are pushed back to their initial position by the rams 36 and 36a fed from an auxiliary hydraulic pressure generator as were fed the cylinders 26, 28 and 33 of the first embodiment. In this optional design, rods 37 act only as guide members to the cradles.

In the two embodiments described, the three cylinders of the hydraulic actuator unit B and the rams which actuate the sliding cradles and the center tool of the forging apparatus may advantageously be dimensioned so as to multiply the total power for upsetting and offsetting movements and obtain a higher total thrust than the press tonnage. In fact, if we call P the maximum stroke of the movable crosshead of the press excluding the height of the actuator unit and C the maximum stroke of the sliding cradles, we find that, in practice ,P/C 2. If the cross-sectional surface of the connected cylinders is so designed that the complete stroke P of the press ram produces only a translation of amplitude C of each sliding cradle the force applied to the two cradles is multiplied by P/C and therefore is more than twice the press tonnage.

The forging apparatus according to this invention is not necessarily actuated by a press the power of which is taken off by a three-cylinder actuator unit. It is obvious that the rams which actuate the sliding cradles and the center tool can be supplied with hydraulic working fluid from a suitable hydraulic pressure generator adapted to control the upsetting and offsetting movements and to obtain the desired relationship between them. Thus a self-contained C.G.F. apparatus is obtained which therefore can be actuated without the assistance of a forging press.

The following advantages inter alia are derived from the apparatus of this invention:

1. The new C.G.F. forging apparatus is mounted in a fixed position adjacent to the press and when crankshafts have to be forged one has only to install the three-cylinder hydraulic actuator unit on the forging press. As a result:

a. The idle time of the forging press at the beginning and at the end of forging a batch of shafts, time which is necessary for installing and removing the three-cylinder actuator unit under the press, is shortened and requires a smaller labor force.

b. The forging apparatus can even be placed in a room separate from and close to the press, provided the handling of the bars from the furnace to the apparatus and back can be performed by a crane bridge of adequate lifting capacity.

2. The three-cylinder hydraulic actuator unit arranged under the upper cross-head of the press is adapted:

a. To transfer the power output from the press to the forging apparatus through hydraulic means and to multiply at least by two the thrust produced by the press b. To distribute this power output among the two sliding cradles and the center tool without any appreciable loss of power by frictional contact as in conventional apparatus. Thus a horizontal thrust corresponding to at least percent of the press tonnage can be applied to the cradles instead of 33 percent with conventional apparatus.

c. To hydraulically actuate the three parts, i.e. the two cradles and the center tool, so as to obtain any desired relationship between upsetting and offsetting movements by changing the starting position of the three rams of the hydraulic actuator unit.

3. Furthermore, as the forging apparatus is not placed under the press it is possible:

a. To remove all the subserviences to the overall dimensions of the apparatus and to dimension it with a view to make the maximum use of the power output of the press due to the tonnage multiplied as mentioned hereinabove.

b. To load the apparatus by a vertical downward movement instead of introducing the bar by an horizontal movement of translation following the center line. Handling is greatly simplified and can be carried out by a smaller crane bridge, even for large crankshafts.

c. To replace the conventional and interchangeable jigs used for holding the throws in proper angular position by a single rotary jig which can be turned at will and allows to forge successively two or three throws in one heat, thus affording a higher output for the equipment and the labor.

4. With a given press operated under full power conditions for an open die forging with a conventional apparatus it is possible to obtain crankshafts of certain dimensions. With the apparatus of this invention actuated by the same press, throws of same dimensions can be forged but they will have considerably smaller machining allowances for, thanks to the thrust multiplication, the webs can be forged in completely closed dies. As a result, the total of a machined crankshaft is considerably reduced.

5. By opening a by pass interconnecting the two lateral cylinders of the hydraulic actuator unit placed under the upper press cross-head, the thrusts on each sliding cradle is equal even if one upset stroke is longer than the other. Thus a stroke of the sliding cradles can forge two adjacent flanges of different sizes or one throw with two webs of different shape. In this case the movements of the two cradles are not symetrical 6. It is possible to add auxiliary cylinders helping to actuate the two sliding cradles, exactly as in conventional apparatus.

7. The forging apparatus according to this invention can be actuated without using a press if the cylinders are supplied with fluid from a suitable hydraulic pressure generator.

Although the present invention has been described in conjunction with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the invention and appended claims.

I claim:

1. An apparatus for forging crankshafts or other forgings having upset and/or offset parts, according to the so-called continuous grain flow process from a barshaped blank, with reduced machining allowances, which comprises on the one hand a forging machine proper equipped with a pair of lateral dies adapted to grip spaced portions of the bar-shaped blank, a first actuator means for causing said dies to slide horizontally towards each other for upsetting the metal, and a central tool adapted to offset the intermediate portion of said bar for forging the crankpin, a second actuator means for moving said central tool vertically between said lateral dies, and on the other hand a separate three-cylinder actuator unit disposed under a conventional forging press for hydraulically transmitting the press power output to the forging apparatus.

2. A forging apparatus as set forth in claim 1, wherein said lateral dies are divided into three parts and mounted in cradles adapted to slide towards and away from each other on a base member, the first and lower part of each die being rigidly secured to the relevant cradle and the second and third parts constituting the upper parts of the die being hingedly connected to the lower portions of each cradle and a pair of hydraulic actuators for actuating said second and third parts.

3. A forging apparatus as set forth in claim 1 comprising means for sliding said central tool vertically to offset the metal of the bar-shaped blank and a pair of jaws on said central tool mounted for pivotal movement, a pair of hydraulic actuators controlling said pivotal movement and a pair of dies on saidjaws to grip the central portion of the bar to be forged.

4. A forging apparatus as set forth in claim 3, wherein means are provided for locking said jaws in position for preventing said dies from opening when the bar is gripped during the forging operation.

5. A forging apparatus as set forth in claim 4, wherein said dies supported by said sliding cradles have set in th latthrowtob for edint e ra ksh t.

i. 5 Forging apparatfis a% set fbrt h iii claim 6,

wherein said bar-shaped blank to be forged is introduced vertically downwards into the apparatus, and means for opening said cradles for receiving at their top the blank either plain or formed with preliminary swells separated by constrictions.

8. A forging apparatus as set forth in claim 1, wherein said three-cylinder hydraulic actuator is overpowered by the movable cross-head of a conventional forging press to cause said actuators to direct the hydraulic fluid contained therein into the cylinders controlling the forging movements of the apparatus.

9. A forging apparatus as set forth in claim 8, wherein a by pass is provided for interconnecting the actuators controlling said lateral sliding cradles to equalize the thrust applied thereto even if one upset forging stroke is longer than the other when forging a crank throw having two different webs.

10. A forging apparatus as set forth in claim 9, wherein the communicating cylinders of said actuator unit and of the forging apparatus have bore diameters and working strokes calculated so that the thrust of the forging press is multiplied by at least two.

11. A forging apparatus as set forth in claim 10, wherein means are provided for presetting the initial positions of the two lateral rams of said three-cylinder actuator unit controlling said lateral cradles and of the central ram of said distributor unit controlling said central tool to synchronize the offsetting and upsetting movements at a predetermined value depending on the shape and size of the throw to be forged, said synchronization being intended for equalizing the upsetting strokes.

12. A forging apparatus as set forth in claim 11, wherein auxiliary hydraulic actuators are provided for reinforcing the upsetting thrust.

13. A forging apparatus as set forth in claim 5, wherein hydraulic cylinder-and-piston actuators are provided for producing the movements of the various movable component elements of the apparatus, except the forging movements proper, said last-named actuators being fed from a separate generator of compressed hydraulic fluid. 

1. An apparatus for forging crankshafts or other forgings having upset and/or offset parts, according to the so-called continuous grain flow process from a bar-shaped blank, with reduced machining allowances, which comprises on the one hand a forging machine proper equipped with a pair of lateral dies adapted to grip spaced portions of the bar-shaped blank, a first actuator means for causing said dies to slide horizontally towards each other for upsetting the metal, and a central tool adapted to offset the intermediate portion of said bar for forging the crankpin, a second actuator means for moving said central tool vertically between said lateral dies, and on the other hand a separate three-cylinder actuator unit disposed under a conventional forging press for hydraulically transmitting the press power output to the forging apparatus.
 2. A forging apparatus as set forth in claim 1, wherein said lateral dies are divided into three parts and mounted in cradles adapted to slide towards and away from each other on a base member, the first and lower part of each die being rigidly secured to the relevant cradle and the second and third parts constituting the upper parts of the die being hingedly connected to the lower portions of each cradle and a pair of hydraulic actuators for actuating said second and third parts.
 3. A forging apparatus as set forth in claim 1 comprising means for sliding said central tool vertically to offset the metal of the bar-shaped blank and a pair of jaws on said central tool mounted for pivotal movement, a pair of hydraulic actuators controlling said pivotal movement and a pair of dies on said jaws to grip the central portion of the bar to be forged.
 4. A forging apparatus as set forth in claim 3, wherein means are provided for locking said jaws in position for preventing said dies from opening when the bar is gripped during the forging operation.
 5. A forging apparatus as set forth in claim 4, wherein said dies supported by said sliding cradles have forging cavities formed therein and forging faces closing said cavities, said cavities and faces cooperating to constitute at the end of the forging movement a closed die unit for shaping the webs of the crank throws close to the final dimensions of the machined crankshaft.
 6. A forging apparatus as set forth in claim 3, comprising in one of said cradles a die member rotatably mounted and driven from a motor-reducer unit through a suitable transmission for the purpose of accurately setting the last throw to be forged in the crankshaft.
 7. A forging apparatus as set forth in claim 6, wherein said bar-shaped blank to be forged is introduced vertically downwards into the apparatus, and means for opening said cradles for receiving at their top the blank either plain or formed with preliminary swells separated by constrictions.
 8. A forging apparatus as set forth in claim 1, wherein said three-cylinder hydraulic actuator is overpowered by the movable cross-head of a conventional forging press to cause said actuators to direct the hydraulic fluid contained therein into the cylinders controlling the forging movements of the apparatus.
 9. A forging apparatus as set forth in claim 8, wherein a by pass is pRovided for interconnecting the actuators controlling said lateral sliding cradles to equalize the thrust applied thereto even if one upset forging stroke is longer than the other when forging a crank throw having two different webs.
 10. A forging apparatus as set forth in claim 9, wherein the communicating cylinders of said actuator unit and of the forging apparatus have bore diameters and working strokes calculated so that the thrust of the forging press is multiplied by at least two.
 11. A forging apparatus as set forth in claim 10, wherein means are provided for presetting the initial positions of the two lateral rams of said three-cylinder actuator unit controlling said lateral cradles and of the central ram of said distributor unit controlling said central tool to synchronize the offsetting and upsetting movements at a predetermined value depending on the shape and size of the throw to be forged, said synchronization being intended for equalizing the upsetting strokes.
 12. A forging apparatus as set forth in claim 11, wherein auxiliary hydraulic actuators are provided for reinforcing the upsetting thrust.
 13. A forging apparatus as set forth in claim 5, wherein hydraulic cylinder-and-piston actuators are provided for producing the movements of the various movable component elements of the apparatus, except the forging movements proper, said last-named actuators being fed from a separate generator of compressed hydraulic fluid. 